The present invention relates to a rotor for pulping and straining machines for food products.
Machines for extracting juices and purées from plant or even animal products essentially consist of a filter or sieve, usually a perforated metal plate, which is cylindrical or conical in shape, and a rotary element (rotor) which turns within the sieve in such a way as to separate the particles that pass through the holes in the sieve from those that do not, the latter being discharged from the sieve as waste.
The rotor is a very important part of the system because the part of the product that has to be extracted usually adheres very strongly to the waste (for example, the flesh and peel of a fruit) and the main function of the rotor is to separate them.
The rotor usually comprises a central hub attached to a power driven shaft and is equipped with a certain number of blades that act on the product in the machine, causing it to rotate within the sieve.
Rotor components vary greatly in shape and size but all rotors known in prior art, whatever their shape, are designed to transmit to the product particles a combined circular and axial motion that causes them to follow a cylindrical or conical spiral path.
The useful part of the product is propelled through the holes in the sieve mainly by centrifugal force. All operating conditions being equal, a low viscosity product will be separated out more easily than one with a high viscosity.
Indeed, highly viscous products tend to form a layer that adheres to the walls of the sieve and makes it more difficult for the useful part of the product to pass through the holes.
This behaviour means that machines of this kind cannot be used on high-viscosity products (for example, banana purée) and, even in the case of medium-viscosity products, reduces machine efficiency.